TEMPERATURE PROFILE DURING SPONTANEOUS APERIODIC OPTICAL BISTABILITY OSCILLATIONS IN LEAD MAGNESIUM NIOBATE

Spontaneous aperiodic oscillations in transmitted and reflected light under steady laser illumination are produced by ferroelectrics includi ng lead magnesium niobate (PMN) and lanthanum modified lead zirconium titanate. Interferometric measurements of the refractive index profile within a single crystal of PILIN by means of a 632.8 nm plane-wave he lium-neon probe beam during simultaneous illumination by a focused 514 .5 nm argon laser beam yield a time-dependent temperature profile of t he sample. Comparison with theoretical model calculations gives a valu e of 0.65 +/- 0.05 W m(-1) K-1 for the thermal conductivity and allows prediction of the number of oscillations as a function of incident po wer, spot size and sample thickness.